Rock drill



Oct. 1, 1929..

E. G. GARTINl Rocx pRILL Filed June 16. 1927 Atty.

Patented Oct. 1 1929 rrED STATES PATENT OFFICE LMER GARTIN, OF CLARElVIONT, NEW HAMPSHIRE, ASSIGNOR TO SULLIVAN MACHINERY COMPANY, A CORPORATION MASSACHUSETTS ROCK DRILL implication med :ruine` 16,

My invention relates to rock drills. It has for an objeotto provideimproved means for controlling the supply of actuating luid to the percussive motor of a rock drill. Another object is to provide an improved throttle valve structure of the type adapted to be held on its seat by fluid pressure wherein means are provided for obtaining a -very sensitive control of the valve opening.

In the accompanying drawings I vhave lshown for purposes of illustration one form which my invention may assume in practlce.

In these drawings, v Fig. 1 shows a rock drilling tool in plan view having my improved throttle valve structure associated therewith, the valve structure and adjacent parts being shown in section to facilitate illustration.

Fig. 2 is a detail sectional view lof the 2 0 .throttle valve structure showing the samein closed position.

Fig. 3 is a view similar to Fig. 2, showing the valve in its initial opening position.

Fig. 4 \is also a view similar to Fig. 2 but showing the valve in intermediate opening position.

Fig. 5 is a detail view of the valve showing the valve stem in section.

In the illustrative form of my invention I y have shown the same associated with a'rock drilling tool which may be of any well known type employing adrilling motor generally designated by the numeral 1 for actuating a drill steel .2. Thel drill steel is held in position in a chuck housing `3 which has connected thereto a suitable drill steel retainer 4 in a well known manner. The rear end of the drilling motoris closed by ahead block 5 h'aving operating handles 6 formed integral therewith. 'A portion of the hammer piston 7 and its cylinder 8 are also illustrated. The chuck housing member, cylindermember and head block 'arey held together by theusualsside rods 9. The means Jfor supvplying pressure iuid to the cylinder 8 com-` prises the usual hose connection 10, suitable passages 11 in the headeblock communicating with other'passages in the cylinder member (not shown), a usual uid distribution valve 1927. serial No. 199,242.

12, and distribution is indicated at 13..

My improved throttle valve structure comprises a valve casing 14 having a cylindrical bore 15 and a conical seat 16. The throttle 55 valve 17 is reciprocably mounted in the valve casing and hasjsuitable means Jfor guiding the same comprising a stem 18 extending through a bore 19 in the valve casing and head block. This valve isprovided with a conical portion 6o 20 for cooperation withthe conical seat 16 and a cylindrical portion 21 litting in the cylindrical bore 15. This portion 21 has formed therein a narrow slot 22 of uniform cross section and V-shaped notches23 increas- 65 ing in cross sectional area toward the. outlet side of the valve. A circumferential recess 24 isalso formed on the valve at the baseA of the conical portion and communicates with the narrow slot 22. The valve casing has a threaded opening 25 for receiving a removable plug 26 to make the valv'e easily accessible. This plug 26 has a recess 27 in which is received a spring .28 one end of which bears passages, one of which against the conical' portion of the valve and 75 tends to hold the same against its seat. The means for operating the throttle valve comprises a manually operatedlever 29 pivotally mounted at 30 in one of the operating handles 6. As will be apparent from the,drawi.ngs, I

this lever is adapte to'engage the valve stem 19 to reciprocate t e valve.- 1

As a result of my invention it will be clear that improved means have been devised yfor sensitively regulating the flow of pressure Huid to a percussive motor, thereby avoiding the sudden application of highly compressed fluid to the hammer piston together with the undesirable ell'ects of such operation. With my improved valve, the initial movement of 9o the lever 29 `will allow a restrictive quantity of fluid to low through the narrow slot 22, which is of such limited cross section that the motor will be actuated very slowly. 'l'nls position of the valve is shown in Fig. 3.l The initial opening -action also relieves to a certain extent-the u nbalanced fluid pressure on the base ofthe valve, thereby avoiding sudden opening. On further movement of the lever 29 the valve' will move to someposition 100 as shown in Fig. 4, gradually increasing the valve opening to apply the desired power to the percussive motor of the drilling tool. When fully opened, the valve Will be moved to a position in which' the cylindrical portion at the inner end of the seating portion Will he in a position in which floW may take place completely around it.

While I have in this application specifically described one form which my invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be l modified and embodied in various other forms Without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. A throttle valve structure comprising a lvalve casing having a conical seat and a c vlindrical bore, a valve slidably mounted in said casing having a conical portion adapted to be held against said seat' by fluid pressure, said valve also having a cylindrical portion slidable in said bore, said cylindrical portion having a notch of restricted cross section for permitting a limited flow of fluid through'the Valve during' initial opening movement, and other notches of varying cross section-for gradually 'increasing the valve opening during furthermovement thereof,

and manual means for operating said valve.

2. A throttle valve for controlling the suply of fluid to a percussive motor comprislng a valve casing, having a conical seat and a cylindrical bore, a valve slidahly mounted in said casing having a conical portion adapted to be held against said seat by fluid pressure,

a spring in said casing also tending to hold said valve against its seat, said valve also ranged adjacent said conical portion so as' to provide for a restricted opening during initial valve opening movement which may be controlled accurately by the operator.

4. In a. pressure fluid actuated percussive motor, conduit means for conducting pressure fluid to said motor, and control means for controlling the flow of fluid .to said motor comprising a throttle valve structure interposed in said conduit means, said valve structure including a valve casing forming a cylindrical bore and a conical valve seat at one end of said bore, a valve having cylindrical and having a cylindrical portion slidable in said y Lloore, said cylindrical portion having a notch of uniform restricted cross section therein for permitting a flow of fluid through the valve during initial opening movement, and V-shaped notches for gradually increasing the valve opening during further movement thereof, a valve stem projecting from the,

outlet side of said valve through a bore in said casing, and a manually operated operat- 1n lever engaglng said valve stein Vfor operating the valve.

.3. In a pressure fluid actuated percussive motor, conduit means for conducting pressurefluid to said motor, and control means for controlling the flow of fluid to said motor comprising a throttle valve structure inter? posed in said conduit means, said valve structure including4 a valve casing forming a cylindrical bore and a conical valve seat at one end of said bore, a valve having cylindrical and conical portions respectivel cooperating With said bore and seat, said'cy indrical portion having notches therein of varying cross section with the more restricted portions ar- 

